This invention relates to an inking or ink feed control apparatus for use in a printing machine, and more particularly an inking control apparatus capable of preventing leakage of printing ink from an ink reservoir while an inking roller is stopped to rotate and wherein while the inking roller is rotating when a stop button is depressed the inking quantity under this state is stored in a memory device so as to ensure the quantity of ink which was supplied before stop at the time when the rotation of the inking roller is started again.
A prior art inking device of a printing machine comprises an inking roller 11, an inking blade 12 made of a single thin plate and a plurality of adjusting screws 13 for moving the inking blade 12 forward and away from the inking roller, as shown in FIG. 1A, the adjusting screws being spaced from each other in the direction perpendicular to the sheet of drawing.
Where it is desired to remotely control the inking device, the adjusting screws are driven by an electric motor 14 through gears 13.sub.a and 14.sub.a, as shown in FIG. 1B.
Where the inking blade 12 is constituted by a single blade, rotation of an adjusting screw at a certain position influences the relationship between the blade 12 and an adjusting screw, not shown, at another position, thus making it difficult to accurately control the quantity of ink fed. Then, as shown in FIG. 1C, it has been proposed to divide the inking blade 12 into a plurality of sections 12A through 12E and to drive these sections by independent adjusting screws, not shown.
According to a subsequently proposed improvement, the inking device is constructed such that the quantity of ink fed would be determined by a balance between the film pressure of the ink leaking through a gap between the inking roller and the divided inking blades and the flexure of inking blades caused by the adjusting screws. The hydrodynamic pressure is greatly influenced by the viscosity of the ink and the velocity of inking roller, that is the number of revolutions of the inking roller so that in such control device for controlling the quantity of ink fed according to the balance of forces, satisfactory control is difficult. Recently, adjusting pieces having metal edges that can be considered as split solids have been substituted for the split thin plate blades for controlling the gaps between the adjusting pieces and the inking roller.
According to another prior art control device shown in FIG. 2, ink 28 in an ink reservoir is fed through a small gap between an inking roller 21 and adjusting pieces 22 actuated by adjusting screws 23. Each adjusting piece is urged against one end of each adjusting screw 23 by a spring 24 interposed between an arm 22A integral with the adjusting piece 22, and the stationary frame F. Each adjusting piece is pivotally mounted on a shelf of the stationary frame. The adjusting screws are rotated by electric motors 25.
This construction can reduce the adverse effect of the viscosity and flow speed of the ink upon the quantity of ink fed through small gaps between adjusting pieces and the inking roller 21.
The prior art control device shown in FIG. 2 accompanies a problem not found in that shown in FIG. 1. More particularly, according to the prior art control device utilizing thin blades, since the quantity of ink is controlled by the balance of forces, as the inking roller stops, the ink film pressure disappears so that the blades which have been maintained in their operating positions by the flexure given to the blades by adjusting screw rods would be urged against the periphery of the inking roller thus preventing the leakage of the ink from the ink reservoir.
Substantially rigid adjusting pieces shown in FIG. 2 do not flex to any appreciable amount, the gaps between them and the inking roller are not influenced by the rotation and stoppage of the inking roller with the result that ink leaks through the gaps a predetermined time after the stoppage of the inking roller.
The ink thus leaked enters into the driving member of the inking roller thus damaging the same. When the printing machine is stopped over a long time, the loss of ink is substantial.